1. Field of the Invention
The present invention relates to a method and an apparatus of performing tunnel signaling over an IP tunneling path. More particularly, the present invention relates to a method and an apparatus of performing tunnel signaling by generating and transmitting over an IP tunneling path a tunnel signaling flow corresponding to an end-to-end signaling flow.
2. Description of Related Art
As Internet technologies have spread, a next-generation communication network is being developed as an “all-IP” network having a structure to which Internet Protocol (IP)-based core networks and various access networks are integrated. In the all-IP network, a wired network such as public switched telephone network (PSTN) and a wireless network supporting, for example, International Mobile Telecommunication-2000 (IMT-2000) are linked to the IP-based core network to function as one integrated IP network.
Integration of different types of networks frequently occurs between a network supporting an IP version 6 (IPv6) address system used for supporting mobility and quality-of-service (QoS), and a conventional IP version 4 (IPv4) network, as well as between an IP network and a non-IP network. Accordingly, a network linking technology for providing an integrated Internet service through an entire network comprising network apparatuses supporting IPv4 and network apparatuses supporting IPv6 is required.
An IP tunneling technology has been regarded as a technology for achieving the integration between an IP network and a non-IP network or IP networks of different types. IP tunneling indicates an encapsulation method of transmitting a packet via a virtual pipe between two nodes on a network. A packet transmission path between the two nodes is called an IP tunneling path or an IP tunnel. Packets transmitted over the IP tunneling path include conventional data packets and signaling packets containing signaling messages for performing particular operations such as QoS and resource reservation.
Typically, a conventional data packet is transmitted over the IP tunneling path by adding a tunnel IP header to a data packet in a suitable form according to a type of network forming the IP tunneling path. For example, when an IPv6 data packet passes an IP tunneling path operating according to an IPv4 protocol, an IPv4 header including addresses of both end points of the IP tunneling path is added to the IPv6 data packet.
However, the described method has an aspect not suitable for transmitting a signaling packet forming a signaling message associated with maintaining and managing a network. Specifically, according to the described method, it is not possible to reflect an operation associated with the signaling message on the IP tunneling path by dealing with a signaling packet as a conventional data packet. For example, since information associated with operations such as reserving network resources to perform QoS with respect to an IP tunneling path and transmitting a router alert option or a certain protocol number is encapsulated by a tunnel IP header, it is not shown on nodes on the IP tunneling path. Therefore, the described signaling operations may not be performed over the IP tunneling path.
In addition, as in the case of one of the conventional QoS methods, when classifying a data packet transmitted over an IP tunneling path according to a service flow type corresponding to the data packet to perform scheduling for each type, if an IP packet transmitted over the IP tunneling path is encapsulated by a tunnel IP header, the service flow type is not recognized on the IP tunneling path. Therefore, the described signaling operations may not be suitably performed.
On the other hand, a User Datagram Protocol (UDP) header may be added for recognizing a QoS data packet on a tunneling path. However, since the UDP header is relatively large, there is a considerable increase in overhead by adding the UDP header to all packets passing the IP tunneling path. Particularly, this type of tunneling method is not suitable since the overhead due to adding the UDP header becomes larger with respect to a service of transmitting a small packet, such as voice over IP (VoIP).
On the other hand, there has been disclosed a method of recognizing an encapsulated message on an IP tunneling path by encapsulating a packet using a Security Parameters Index (SPI) field of an IP Security (IPSEC) protocol proposed by the Internet Engineering Task Force (IETF) for secure transmission and reception of packets in an IP layer. According to this method, a fine signaling over an IP tunneling path is possible without any overhead due to adding an additional header. However, the method can be applied to only an IP tunneling path supporting the IPSEC protocol.
A conventional resource reservation protocol (RSVP) using the described methods of adding an IP header or an UDP header to an IP packet, or using an IPSEC SPI field cannot effectively support mobility of a host, since the conventional RSVP does not support sender-initiated signaling that will be described later, and does not have consideration for the mobility, for example, a session identifier value varies with handoff of a mobile node.
Accordingly, an interest for a method which can effectively perform tunnel signaling and can support mobility and the QoS has increased.
Since mobile Internet is on the verge of being widely introduced, a method of supporting mobility of Internet apparatuses is enjoying brisk research, however an optimal method of performing tunnel signaling on a mobile IP tunneling path formed of network apparatuses based on a mobile IP has not yet been provided.
Accordingly, in order to solve the above described problem, there is a need for an improved method of effectively performing tunnel signaling, the new method generating a tunnel signaling flow corresponding to an end-to-end signaling flow, and transmitting the generated tunnel signaling flow through an IP tunneling path.